Stroke adjusting means

ABSTRACT

A STROKE ADJUSTING MECHANISM FOR A CONTROLLED VOLUME PUMP PROVIDED BETWEEN THE DRIVING MEANS AND THE DRIVEN MEMBER INCLUDING AN ECCENTRIC SHAFT, A CAM SECURED THERETO AND CONNECTED TO SAID DRIVEN MEMBER AND ADJUSTING MEANS CONNECTED TO ONE END OF THE ECCENTRIC SHAFT THROUGH A BEARING TO DISPLACE SAID ECCENTRIC SHAFT ALONG THE AXIS THEREOF, AND WHEREIN SAID CAM IS FORMED WITH A CAM SEAT THEREIN ADJACENT TO AND ALIGNED WITH THE DRIVEN   MEMBER AND SAID DRIVING MEANS IS COUPLED TO SAID CAM BY A KEY RIDING IN SAID CAM SEAT FOR THE ROTATION OF SAID CAM AND THE DISPLACEMENT OF SAID DRIVEN MEMBER.

Feb. 9, 1971 TERUO AWA j 3,562,779

STROKE ADJUSTING MEANS Filed DC. 23, 1968 2 Sheets-sheaf]. v

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Feb. 9, 1971 TERUO OIKAWA 3,562,779

STROKE ADJUSTING MEANS I Filed Dec. 25, 1968 2Sheets-Sheet 2 United States Patent 01 3,562,779 Patented Feb. 9, 1971 ice STROKE ADJUSTING MEANS Teruo Oikawa, Murayama-shi, Japan, assignor to Nippon Kikai Keiso Kaisha, Ltd. Filed Dec. 23, 1968, Ser. No. 786,099 Claims priority, application Japan, Dec. 23, 1967,

Int. Cl. F16h 35/08; F04b 9/08 US. Cl. 74--837 1 Claim ABSTRACT OF THE DISCLOSURE A stroke adjusting mechanism for a controlled volume pump provided between the driving means and the driven member including an eccentric shaft, a cam secured thereto and connected to said driven member and adjusting means connected to one end of the eccentric shaft through a bearing to displace said eccentric shaft along the axis thereof, and wherein said cam is formed with a cam seat therein adjacent to and aligned with the driven member and said driving means is coupled to said cam by a key riding in said cam seat for the rotation of said cam and the displacement of said driven member.

SUMMARY OF THE INVENTION (a) Field of the invention The present invention relates to an improvement on the invention disclosed in the United States Pat. No. 3,398,691.

(b) Description on the prior art and disadvantage in the prior art Prior stroke adjusting means according to the invention disclosed in the United States Pat. No. 3,398,691 has the shortcoming that the slant shaft 51 as shown in FIG. 1 of said patent, and the cam member 2 have a tendency of unendurable wear in regions of their engagement, because an abnormal offset load is applied to the slant shaft 51 (or because rotational movement of the cam member about the slant shaft 51 by dint of the piston force results in a factor of unstable conditions, for example, a condition where the crank is thrust up, and further because the additional development of the thrust force is caused by a condition where the crank is thrust up).

(c) Technical subject matter of this invention The present invention has for its object to eliminate the above-mentioned shortcoming, and the gist of this invention resides in stroke adjusting means which is characterized in that a cam member has, on its one side, a key seat which is disposed in an aligned relation to the longitudinal line of a connecting rod, and a key is fitted in said key seat so that the driving torque is loaded on the cam member through the key.

BRIEF EXPLANATION OF THE DRAWINGS FIG. 1 is a sectional view illustrating a preferred embodiment of the present invention;

FIG. 2 is a diagrammatic view showing the fashion where the piston force is applied to the cam member in connection with the embodiment of FIG. 1;

FIG. 3 is a schematic explanatory view of FIG. 2;

FIG. 4 is a diagrammatic view showing the fashion where the piston force is applied to the cam member in connection with the invention disclosed in the United States Pat. No. 3,398,691;

FIG. 5 is a schematic explanatory view of FIG. 4.

DETAILED EXPLANATION OF THE INVENTION Referring now to FIG. 1 wherein an eccentric shaft is generally shown at 10, the eccentric shaft 10 comprises a slant shaft 13 having uppermost and lowest extremities on which are integrally formed rotary elements 11 and 12, respectively. The eccentric shaft 10 is, thus, comprised of the slant shaft 13 having a longitudinal axis P-P located at an incline of fixed angle 0 with respect to a line X-X' which includes the central axial lines of the rotary elements 11 and 12 which are respectively, secured on the opposed extremities of the slant shaft 13. It will be apparent that the longitudinal axis P-P' is intersected at a point substantially halfway along its length by the line X-X common to the central axial lines of the rotary elements 11 and 12. It will be further understood that, although the slant shaft 13 is shown in FIG. 1 in the form of a round bar, it may be of the other preferable profile. A cam member is indicated at 14 and is provided therein with a hole 15 through which the slant shaft 13 is extending. It will be understood that the question of whether the hole 15 is at or out of the center of the cam member 14 is not critical. Preferably, the hole .15 in the cam member 14 is extended in such an orientation that the cam member 14 is positioned in a plane perpendicular to the central axial line X-X of the rotary element 11 while the slant shaft -13 may be snugly fitted in the hole 15 of the cam member 14. A connecting rod is indicated at 16 and is drivingly moved in a reciprocating manner 'by means of the cam member 14 which is rotated by the slant shaft 13. Further, shown in FIG. 1 are a lead screw .17, a shaft guide 18, a shaft sleeve '19, a worm wheel 20 secured around the shaft sleeve 19 by means of a key 21, a bearing means 22, a housing 23 and a power transmission key 21'. Now, the slant shaft 13 of the eccentric shaft 10 is fitted in the cam member 14, as mentioned above, so that the eccentricity of the cam member 14 may be varied by displacement of the cam member 114 along the line X-X' relative to the cam member 14. Driving power is supplied to a 'worm shaft 24 directly connected to a motive unit and then is reduced in speed to a predetermined rotational speed through the reduction gear means 24 and 20 thereby causing the cam member .14 to rotate at the reduced rotational speed. As a result, the rotational movement of the cam member 14 results in the reciprocating movement of the connecting rod 16. Whereas, the lead screw 17 for adjusting stroke is operatingly connected to the eccentric shaft 10 through the bearing means 25 and therefor the rotational movement of the lead screw 17 is transmitted to the eccentric shaft 10 through the shaft sleeve 19, the cam member 14 and the shaft guide 18 so as to permit the eccentric shaft v10 to displace along the direction of the line X-X. According to the present invention, the stroke length may be adjusted over 0%- 100% in an infinite or linear manner. FIG. 1 shows the condition where the length of the stroke is at zero.

In the preferred embodiment shown herein, the cam member 14 has, on its one side 40 opposed to the driving member, a key seat 41 which is disposed in aligned relation to a longitudinal line of the connecting rod 16. Closely fitted in the key seat 41 is a key 42 whereby the driving torque is applied to the cam member 14 through the key 42. The lead screw 17 is operatingly connected to the eccentric shaft 10 through the bearing means 25 and also the lead screw guide 26 serves as a locking nut for the lead screw 17. It will be thus understood that the lead screw 17 is operatingly connected to a stroke adjusting shaft 30 through a key 27, a worm gear wheel 28 and an adjusting worm 29. The stroke adjusting shaft 30 is provided on the outer end thereof with a manually operable hand-Wheel 31 so that rotation of the handwheel 31 results in the longitudinal displacement of the lead screw 17 to displace the eccentric shaft 10 along the axis thereof.

The diagrammatic views of FIG. 2 to illustrate a comparision between the arrangements disclosed in the United States Pat. No. 3,398,691 and in the present invention in connection with a fashion where the piston force is loaded against the cam member.

Reference will be first made to FIGS. 4 and 5 showing the fashion where the piston force is loaded against the cam member in the invention disclosed in United States Pat. No. 3,398,691. If now, assuming that the piston force is loaded against the cam member on a slant from the right-upper side and further three points A, B and C, spaced and located on a common central traverse line Y-Y of the cam member as shown in FIG. 4, are taken into consideration, forces FA, PB and P which are locally loaded against the three points A, B and C when the stroke is at its maximum to develop full-load torque are in the following relationship (refer to FIG. 5);

hence,

FB: 2F

It will be thus apparent from the above-mentioned equations that the particular points (B) is subjected to the maximum load or piston force.

Reference will be then made to FIGS. v2 and 3 showing the fashion where the piston force is applied to the cam member in the present invention. In this case, as shown in FIG. 2, the greater part (about 80% to 90%) of the piston force may be preferably withstood by means of a particular point D or the key 42 so that the point B will be substantially free from the piston force. Namely, the relationship of the locally loaded forces against the three spaced points on the cam member may be expressed by the following equations;

hence,

Thus, the arrangement according to the present invention has for its feature to make the key 42 bear the piston force, conventionally applied to the slant shaft 13 and the cam member 14, with the result that the slant shaft 13 may be substantially freed from the unfavourable load due to the piston force. Considering such feature in the power transmission aspect, the power from the motive unit, as for the invention disclosed in the United States Pat. No. 3,398,691, has been transmitted from the worm gear to the slant shaft through the course including the worm gear the sleeve-ethe N-crank+ (the slant shaft) the cam member. Whereas, in accordance with the present invention, such power is transmitted 4 through the course including the worm gear wheelthe sleevethe cam member, with leaving out the N-crank, 'whereby the piston force is lightened in the load imposed thereto.

Since the stroke adjusting means of the present invention is constructed as described above, and in particular constructed such that the driving torque may be applied to the cam member 14 through the key 42 so as to lighten the load imposed on the slant shaft '13. Thus, the present stroke adjusting means has advantages in which the cam member is protected from the unendurable wear on its particular locality, and in which the longitudinal movement of the slant shaft 13 by dint of the cam member 14 may be smoothly effected whereby the stroke is adjusted automatically and certainly.

Various other modifications, alternative constructions and equivalents may be employed without departing from the true spirit and scope of the invention, as exemplified in the following claim.

I claim:

'1. In a stroke adjusting means for a controlled volume pump or the like having driving means, a shaft sleeve coupled to said driving means for rotation thereby, eccentric shaft means having at least one end portion secured within said shaft sleeve for rotation therewith and an oblique shaft portion secured at one end to said end portion and disposed at an oblique angle to the longitudinal axis of said eccentric shaft means, said end portion being slidable within said shaft sleeve for the longitudinal 3O displacement of said eccentric shaft, a cam formed with an oblique aperture therethrough of said oblique angle, said aperture being adapted to slidably receive said oblique shaftportion, said cam being adapted for displacement in a direction transverse to said eccentric shaft means along the longitudinal axis in response to the displacement of said eccentric shaft along said axis and for rotation about said axis, adjusting means for selectively displacing said eccentric shaft means along the longitudinal axis thereof and driven means coupled to said cam for reciprocal displacement in response to the rotation of said cam, the improvement which comprises said cam being formed on the side thereof facing said shaft sleeve with a key seat, said key seat extending in said transverse direction; and a key coupled to said shaft sleeve and positioned in said key slot for the application of driving torque to said cam from said driving means through said shaft sleeve and key.

References Cited UNITED STATES PATENTS 

